A wearable device can be worn by controllers or passengers in vehicles. A passenger may wish to enjoy full use of the wearable device, such as by interacting with applications, receiving notifications, or issuing commands by voice or touch. In contrast, a user controlling a vehicle may not want, or may not be able, to safely interact with the wearable device in the same ways that a passenger could. For example, a vehicle controller may not be able to take his or her eyes off the road or hands off the steering wheel to interact with the device.
The wearable device can also include motion sensors to collect data about the wearable device's position and orientation in space and to track changes to the wearable device's position and orientation over time. Because a user can wear the wearable device, the motion data can provide information about the user's movements. For example, when a user is running, the user's arms are typically swinging back and forth over a particular distance and at a particular frequency. If the user wears the wearable device on the user's wrist, the wearable device may be able to infer that the user is running by sensing the way the user's arm moves back and forth.
Because controllers and passengers may prefer or require different uses of the wearable device, it may be advantageous to detect automatically whether a user is controlling a vehicle and adapt its behavior accordingly to better suit the user while the user is controlling a vehicle.